Determining the Water Potential of a Potato Chip
Aim: To determine the water potential of a potato chip
Background knowledge
What is water potential?
Water potential is the measure of the tendency of water to move from
one place to another. Like the movement of water from potato chip to
surrounding solution or vice versa. Water always moves from an area of
high water potential to a region of lower water potential.
The addition of solutes decreases water potential making it more
negative. Therefore it is less likely to move from one place to
another. Pure water has a water potential of zero, by adding solutes
you make the water potential more negative. In plants water potential
depend on two things, Osmotic potential (due to presence or absence of
solutes) and pressure potential (due to turgor pressure).
To work out water potential you use this equation
Water potential = solute potential + pressure potential
Ψ = Ψs + Ψp
In my experiment the water potential equals the solute potential
(solute potential is always negative), as the pressure potential is
negligible. However pressure potential is pressure exerted when water
enters a cell and makes it turgid. Increasing pressure increases the
tendency of water to move, therefore increases water potential.
Pressure potential is always positive therefore making water potential
less negative. In my experiment I am not going to do anything to
affect the pressure, as this will disallow me to find the water
potential using the method I have selected.
What is osmosis?
Osmosis is the movement of water molecules from a high water potential
to a low water potential through a selectively permeable membrane.
This continues to happen to till dynamic equilibrium is reached and
the water potential on both sides of the partially permeable membrane
is the same.
Plant cells always have a strong cell wall surrounding them, which is
the selectively permeable membrane. When water moves in to the cell by
osmosis it starts to swell, but the cell wall prevents it from
Investigating Osmosis in Potatoes Aim: Investigate the movement of osmosis through a selectively permeable membrane, in this case potato. Introduction: Osmosis is the movement of water through a semi permeable membrane. The water passes from an area of high concentration to an area of low concentration, until the two concentrations are equal in concentrations of water. Many cell membranes behave as semi permeable membranes, and osmosis is a vital part in the movement of liquids in living organisms, for example, in the transport of water from the soil to the roots in plants.
to the marble chips. I will have 30 ml of mixture and split it in to
Osmosis is a type of diffusion which is only applied on water and is a passive process which does not require an input of energy from the cell; this is because materials are moving with the concentration gradient. Osmosis is a process that occurs at a cellular level, which entails the spontaneous net movement of water through a selectively permeable membrane, from a region of high to low water concentration, in order to equalise the level of water in each region. This form of diffusion takes place when the molecules in a high concentration are too large to move through the membrane. The term semi-permeable or selectively permeable means that some substances can easily pass through the cell membrane, whereas others cannot. The significance of osmosis to cells is great, since it is the osmotic pressure that maintains the shape of an animal cell and provides support in the plant cells. Many factors affect the rate of osmosis including size of particles and temperature however in this particular experiment the factor investigated is the concentration of sodium chloride. Tubes of potatoes will be used to demonstrate the fact...
If a plant cell is places in a hypotonic solution the cell has a lower water concentration to that of the solution. Water will move into the cell by osmosis from a high water concentration outside the cell to a lower water concentration inside the cell through a selectively permeable membrane. The cell becomes turbid
there would be no flow of water into or out of the cell so the cell
Once upon a time, in a kingdom far away far away… actually it wasn't that far away, the kingdom is currently known as Oregon, but this story starts in the year 1256.
The. So if there is a lot of salt dissolved into water surrounding the organism (in this case a potato chip) then water particles from. other cells are going to attempt to equal the concentration of water. in the solution with the water concentration in the cell. Therefore most of the water from the cells of the potato chipping will change in mass, depending on the concentration of solution.
... els of sucrose solution to distilled water (see molarity table above) and I placed each of the mixtures into the correct beakers. 5. Then I weighed all the potato chips on an electronic balance (see results) and recorded the results. 6. I placed 5 pieces of potato into each beaker and left them for approx 36 hrs. 7. After this time I drained out the solutions from the beakers and I carefully placed them in order of molarity on a paper towel. 8. I dried the potato chips gently and then weighed each potato piece and recorded the results. 9. As I had extra time I made a second experiment and also recorded those Results: Molarity (M) Starting Weight (g) (Results 1) Final Weight (g) (Results 1) Percentage Change (%) (Results 1) Start Weight (g) (Results 2) Final Weight (g) (Results 2) Percentage Change (%) (Results 2) These values clearly support my prediction, and even though there are some anomalous results, there is an overall negative trend across the whole set of results, proving them accurate. Analysis of Results: The sucrose concentration of the solution into which the potato tissue is placed affects to what degree it grows or shrinks. As you can see from the graph the results show a clear negative correlation, a very obvious inversely proportional trend. From this a conclusion can be drawn. When the water concentration is high, the potato gains water, as seen by the 0.0 molarity solution. When the water concentration is low, the potato loses weight and therefore decreases in mass, as seen in the 1.0 concentration solution. This proves my hypothesis correct. The results were quite widely ranged, as seen on the graph, wit ......
The materials needed are three small beakers (150 or 250 ml), a potato, a knife to cut the potato into pieces, a ruler to measure the potato, something to weigh the potato pieces, a timer, a calculator, and three solutions: distilled water, 10% sucrose, and 50% sucrose. The point of this experiment is to calculate the percent change in the mass before and after soaking the potato in the three different solutions. Create your own hypothesis before beginning the experiment. My hypothesis is that the potato soaked in water will have a higher mass after soaking, and that the potato soaked in the 10% sucrose and 50% sucrose will remain the same. Make sure to keep up with your measurements since they are needed to determine the mass percent change. The best way to accomplish this is to use the table provided at the end of this sheet to record your results. The first thing you need to cut the potato into three pieces of about two cubic centimeters (cm^3) in length. The second step you need to take is weighing each potato piece and writing down its mass. Next, label the three beakers with the three different solutions used. Then, you need to pour distilled water over one piece of potato, 10% sucrose on another, 50% sucrose on the last piece of potato; each solution needs to be poured on each potato piece until they are completely submerged. After they are submerged: set your timer for an
For my preliminary work, I used a 50 mm piece of potato. It was easy
For the preparation of Part 1, pieces were cut from the potato and were blended. The prepared suspensions were broken cells of the potato used as the extraction. The process of the suspension was the homogenization of the organism and later was centrifuged so that some of the substances reached the bottom (insoluble particles) and used the liquid as the enzyme(Schultz, 2006). The enzyme was brown colored known as the catechol oxidase, and that product can be used to measure the reaction rate using a spectrometer (Schultz, 2006). We started with twice the volume of the stock, so for the case of Part 1 was to begin with 6 ml of full strength enzyme. Two test tubes were used for the dilution. The first contained 5ml of buffered catechol and the
potato cells. In order to find the best way to do this experiment I am
The Effect of Water Concentration on the Mass of Potato Tissue Aim: The aim of this investigation is to discover the effect of water concentration on the mass of potato tissue, and also to investigate the movement of osmosis through potato tissue. Scientific Knowledge: When a substance such as a sugar dissolves in water, the sugar molecules attract some of the water molecules and stop them moving freely. This, in effect, reduces the concentration of water molecules.
Operation: A hydrometer is a measurement instrument used to measure the relative density of liquids, the ratio of a density of a liquid to the density of water.
Osmosis is the passage of water molecules from a weaker solution to a stronger solution through a partially permeable membrane. A partially permeable membrane only allows small molecules to pass through, so the larger molecules remain in the solution they originated in. Solute molecule [IMAGE] [IMAGE] Water molecule [IMAGE] The water molecules move into the more concentrated solution. When water enters a plant cell it swells up. The water pushes against the cell wall and the cell eventually contains all that it can hold.